Time Reversal Invariance Test in Very Slow Neutron Reactions

极慢中子反应中的时间反转不变性测试

• 批准号: 06044111
• 负责人: MASAIKE Akira
• 金额: $ 5.12万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044111/
• 关键词: neutron; transmission; parity; time reversal; matrix element; resonance absorption; polarized filter; capture gamma-ray; proton polarization; 対称性; 中性子; 共鳴反応; 増幅効果; 動的偏極法; ランタンアルミネート

Several experimental tests of parity violation in neutron resonance absorption reactions have been carried out by means of the capture gamma-ray measurement and neutron transmission method using polarized slow neutrons at Los Alamos and KEK in order to determine the weak matrix elements in hadron-hadron interactions. At Los Alamos the determination of weak matrix element has been performed with the help of statistical model of compound nucleus. The likelihood analysis has been done for mean-zero }Gaussian randam variables for the helicity asymmetries in many p-wave resonances interfered with several neighboring s-wave resonances. On the other hand, exit channel interference effects in capture gamma-ray reactions have been measured at KEK.The measurement of the term A_9・sigma_n^^*・k_<gamma>^^* has been made on the p-wave resonance (E_n=0.734eV) of ^<139>La, where sigma_n^^* is the neutron spin direction and k_<gamma>^^* is the direction of emitted gamma-rays. These measurements are usef … More ul to find out the sensitivity of the observables of the time reversal violation.Neutrons have been polarized using the polarized proton and ^3He filters. Protons in ethylene glycol with Cr^V complexes are polarized dynamically in 0.4K and 25KG.A new method of polarization has been developed, in which protons in pentacence-doped naphthalene have been polarized by means of laser excitation and dynamical polarization of a photo-excited triplet state of pentacene in room temperature and in liquid nitrogen temperature.^3He gas has been polarized by means of the optical pumping.It has been found that La nucleus in LaA1O_3, which is a very important nucleus for the test of time reversal invariance, can be polarized by means of the dynamical method. The polarization has been more than 20%.The depolarization of low energy polarized neutrons in holmium crystal has been measured and found not to be so large in the energy region higher than 20 eV.Therefore, the measurement of a 5-fold correlation parameter in the neutron transmission through holmium became feasible. Less

为了确定强子-强子相互作用中的弱矩阵元素，在洛斯阿拉莫斯和KEK利用极化慢中子，采用俘获伽玛射线测量和中子透射法对中子共振吸收反应中的宇称破坏进行了实验测试。在洛斯阿拉莫斯，利用复合核的统计模型进行了弱矩阵元素的测定。对许多p波共振中与相邻s波共振相干扰的螺旋度不对称性，用均值为0}的高斯随机变量进行了似然分析。另一方面，在KEK上测量了捕获伽马射线反应中的出口通道干涉效应。在^<139>La的p波共振（E_n=0.734eV）上测量了A_9·sigma_n^^*·k_<伽马>^^*项，其中sigma_n^^*为中子自旋方向，k_<伽马>^^*为发射伽马射线的方向。这些测量对于找出时间反转违背的观测值的灵敏度是有用的。中子通过极化质子和^3He滤光器被极化。含Cr^V配合物的乙二醇中的质子在0.4K和25KG时动态极化。本文提出了一种新的极化方法，即在室温和液氮温度下，通过激光激发和光激五苯三重态的动态极化，使掺五苯萘中的质子发生偏振。^3气体通过光抽运被极化。发现laa10_3中的La核可以用动力学方法进行极化，它是时间反转不变性检验的重要核。两极分化已经超过了20%。测量了低能极化中子在钬晶体中的退极化现象，发现在20 eV以上的能量区退极化现象不大。因此，测量中子通过钬的5倍相关参数成为可能。少

项目成果

M.B.Johnson: "Microscopic,Model-space Apporoach to Parity Nonconservation in Compound Nuclei" Physics Review. C51. 999-1013 (1995)

M.B.Johnson：“复合核中宇称不守恒的微观模型空间方法”物理评论。

Yi-Fen Yen: "Studies of Gamma Background in a Pulsed Epithermal Neutron Beam and the Neutron-Boron Capture in ^<10>B-loaded Hydrogenous scinti" Proc. of First International Workshop on Accelerator -based Neutron Sources for Boron Neutron Capture Therapy.

Yi-Fen Yen：“脉冲超热中子束中的伽玛背景和^ 10 B负载的氢闪烁体中的中子硼俘获的研究”Proc。

Yi-Fen Yen: "Study of Parity and Time-Reversal Violation in Neutron-Nucleus Interactions)" Proc.of Polarization Phenomena in Nuclear Physics(AIP339,New York,1995). 120-135 (1995)

Yi-Fen Yen：“中子-核相互作用中的宇称和时间反转破坏的研究”Proc.of Polarization Phenomena in Nuclear Chemistry（AIP339，纽约，1995）。

T.Adachi: "Test of Parity Violation and Time Reversal Invariance in Slow Neutron Absorption Reactions" Nuclear Physics. A577. 433-441 (1994)

T.Adachi：“慢中子吸收反应中宇称破坏和时间反转不变性的测试”核物理。

J.N.Knudson: "Neutron Deformation in ^<165>Ho" Physics Review. C50. 909-917 (1994)

J.N.Knudson：“^<165>Ho 中的中子变形”物理评论。